CVE-2026-124317 libexpat through 2.10.0 Out-of-Bounds Read via unknown_toUtf8 and unknown_toUtf16
Medium 6.3
Published
Updated
Check this codebase for CVE-2026-124317 and fix it if it is affected.
What it is: CVE-2026-124317 is a medium-severity vulnerability in libexpat, published on 7 Nov 2026.
Exploitation: There is no known exploitation of CVE-2026-124317 in the wild and no public exploit code.
Affected product: libexpat. No package-level version data is available, so check the vendor advisory linked from the reference page.
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2026-124317/ (Markdown: https://insights.sbomify.com/CVE-2026-124317/index.md)
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-124317?
CVE-2026-124317 is a medium-severity vulnerability in libexpat, published on 7 Nov 2026.
Official description
libexpat through 2.10.0 contains an out-of-bounds read vulnerability in unknown_toUtf8() and unknown_toUtf16() in xmltok.c when handling application-registered unknown encodings. Attackers can supply a document ending in a truncated multibyte sequence so the convert callback reads past the parse buffer, leaking adjacent memory or crashing applications.
Weakness: CWE-126
Which versions are affected by CVE-2026-124317?
How do I fix CVE-2026-124317?
Upgrade to a fixed version.
Is CVE-2026-124317 being exploited?
There is no known exploitation of CVE-2026-124317 in the wild and no public exploit code.
Sources
Also known as AZL-112841, AZL-113119, AZL-113248, DEBIAN-CVE-2026-124317, ECHO-1c7a-4e4f-0368, GHSA-wm22-jw4m-rfcf and 1 more.